Economic evaluation is used to determine the most efficient use of resources by comparing the costs and outcomes of different interventions. Outcomes can be measured by health-related quality of life (HRQoL) and may include both patients and unpaid carers’ HRQoL. Prior research found that incorporating carer’s HRQoL in economic evaluations is uncommon, inconsistent, and relies on limited data and strong assumptions.
A key consideration is whether caregiving causally affects carer’s HRQoL. My literature review indicates a lack of robust evidence. Generally, longitudinal studies suggest a detrimental effect on health/wellbeing, but the benefits derived from caregiving may mitigate its negative effects.
I analysed longitudinal data for patient-carer dyads and found carers’ HRQoL decreased as the patients’ HRQoL decreased and as the duration of care increased. My analysis of a cross-sectional EQ-5D dataset found people providing more hours of care per week have worse HRQoL, even after adjusting for confounders. Both analyses suggest a causal effect of caring on HRQoL and provide inputs for use in economic evaluations in any adult health condition.
Current methods for modelling carers’ HRQoL assume the effect of caring on HRQoL is unidirectional: a negative effect implies any extension to patient survival leads to a carers’ quality-adjusted life year (QALY) loss, a positive effect implies any extension to patient survival leads to a carers’ QALY gain. These approaches force a choice between carers maximising their own HRQoL or the patients’ HRQoL. My new modelling method allows a trade-off between the positive carer’s HRQoL effect of improving patients’ HRQoL and the negative carers’ HRQoL effect of increasing caregiving burden.
I demonstrated that it is possible to identify a causal effect of caring and created a method to include this in economic evaluation. Future research can build on this to address data gaps and explore the transferability of evidence.
